In recognizing Kenyan Geoffrey Mutai's mark of 2:03:02 at the 2011 Boston Marathon as (at the time) the fastest Marathon ever run, the IAAF has noted: Due to the elevation drop and point-to-point measurements of the Boston course, performances [on that course] are not eligible for World record consideration..
There are three types of embryonic cells; endoderm, mesoderm, and ectoderm. In the human body there are many different types of cells, more than two. They are grouped into tissue types. We have four different tissues; connective, nervous, muscular, and epithelial. The two major groups of cell types in the human body are somatic cells and gamete cells. There are three types of embryonic cells; endoderm, mesoderm, and ectoderm. In the human body there are many different types of cells, more than two. They are grouped into tissue types. We have four different tissues;  connective, nervous, muscular, and epithelial.
Part I: Introduction and Astrocyte Glia. There are two major types of cells in the brain: neurons and glial cells. While much is known about neurons that have been studied for more than a century, in-depth glial cell research has only developed over the last decade.